tl;dr: Amazon takes close to half of each sale from third-party sellers through referral fees, fulfillment, and effectively-mandatory advertising, forcing sellers to raise prices to stay profitable. Because Amazon's Fair Pricing Policy penalizes sellers (by removing the Buy Box or suspending them) for offering lower prices on other sites, sellers raise prices everywhere—meaning shoppers pay "Amazon prices" even at Walmart, Target, or direct from the brand. This practice is central to the FTC's 2023 antitrust case against Amazon, set for trial next year.